[unreadable] [unreadable] This prospective, cross-sectional epidemiological study will implement a developmental surveillance system to determine the prevalence of ASD in early childhood using a community-based screening and diagnostic protocol developed and evaluated by the FIRST WORDS(r) Project. Children will be recruited from a representative population-based sample of over 16,000 children born between April 2006 and March 2010 in 12 contiguous counties in the panhandle of Florida, who will be screened with a broadband parent-report surveillance checklist between 9 and 18 months of age. All children who fail and randomly selected children who pass the broadband screen will be invited to complete an autism-specific screen between 10 and 18 months. Two autism-specific screening tools will be used, one based on parent report and one based on an interactive videotaped systematic observation. Case ascertainment will be based a diagnostic evaluation to confirm or rule out ASD at 18 and 30 months of age with children who fail the autism-specific screen. In preliminary studies using this developmental surveillance system in Leon County, 67 children have been identified to date from a prospective sample of over 6,410 children screened between 6 and 24 months who have received a diagnosis of ASD at 30 months of age or older; 64 received a positive broadband screen and 66 a positive autism-specific screen. The following research aims will be addressed: 1) to determine the prevalence of ASD at two ages in early childhood, 18 and 30 months, and two birth cohorts; 2) to estimate validity measures of the broadband parent report and autism-specific screening tools; 3) to compare the autism-specific parent-report screening tool with the autism-specific interactive screening tool; 4) to describe [unreadable] demographic and developmental characteristics of this cross-sectional sample, which will include about 1/2 the birth rate of 2 small urban and 10 surrounding rural counties; and 5) to identify barriers that may impede and strategies to improve the screening and referral process for parents and professionals. Focus groups will be conducted with parents and professionals to seek input on how to improve the screening process and offer better ways to share information about initial diagnosis and access to services. [unreadable] [unreadable] [unreadable]